This work is aimed at producing superior methods for the analysis of catecholamines, indoleamines, and their related biosynthetic/drgradative enzymes. Liquid chromatography with electrochemical detection is the powerful combination which has been selected for this task. This method has already been demonstrated to possess excellent sensitivity and selectivity for such determinations. In particular, wel will be employing this approach to (1) extend existing assays to encompass more metabolites and precursors, (2) monitor in vivo and in vitro enzymatic activities via analysis of appropriate metabolic products, (3) increase the sensitivity of the technique, (4) automate the procedures and optimize the conditions, and (5) demonstrate applicability to both routine and difficult samples.